Abstract
This paper presents a preliminary analysis of the variations of the critical frequency of the F2 region (foF2) and the total electron content (TEC) derived from Global Positioning System (GPS) data. Hourly foF2 values were scaled from ionograms recorded at San Martin (68.1°S, 293.0°E) and the TEC values were derived from GPS observations at O’Higgins (63.3°S, 302.5°E). The database includes measurements obtained under different seasonal and solar activity conditions. The study shows that the daily peak of foF2 occurs around local noon in winter and fall, and in spring a secondary peak is observed around midnight. In summer (January) foF2 reaches its minimum value around the noon sector while the maximum in the diurnal variation of foF2 is located in a time sector close to midnight. This behaviour is observed at low and high solar activity. The semiannual anomaly appears around noon at high and low solar activity and the winter anomaly is not observed. The effect of the solar activity is generally observed in every season. The analysis of the GPS TEC measurements in the same region indicates that the diurnal, seasonal and solar activity variations are similar to those observed in the foF2 values. An analysis of the performance of the IRI model to predict foF2 is also shown using the two IRI options (URSI and CCIR). The comparisons between the experimental values and the IRI predictions show some discrepancies.
Highlights
Three latitudinal regions can be distinguished in the terrestrial ionosphere namely: the equatorial zone, the high latitude and the middle latitude zone in between.The knowledge of the high latitude ionosphere is more limited compared with that of the middle and low latitudes and the known features of the high latitude region have been derived mainly from observations in the Northern hemisphere
This paper presents a preliminary analysis of the variations of the critical frequency of the F2 region and the total electron content (TEC) derived from Global Positioning System (GPS) data
The study shows that the daily peak of fo F2 occurs around local noon in winter and fall, and in spring a secondary peak is observed around midnight
Summary
Three latitudinal regions can be distinguished in the terrestrial ionosphere namely: the equatorial zone (within 20◦ of the magnetic equator), the high latitude (poleward of about 60◦ geomagnetic) and the middle latitude zone in between.The knowledge of the high latitude ionosphere is more limited compared with that of the middle and low latitudes and the known features of the high latitude region have been derived mainly from observations in the Northern hemisphere. The analysis of the GPS TEC measurements in the same region indicates that the diurnal, seasonal and solar activity variations are similar to those observed in the fo F2 values.
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